The present invention relates to a USB connector having a lock mechanism and used for electrically connecting the body of a computer such as a personal computer or a workstation and peripheral equipment including a mouse, a keyboard and so on.
Recently, a mouse, a keyboard, a printer, a scanner, a modem, an external memory and the like as peripheral equipment are connected to one computer body via different interfaces. For example, a mouse and a keyboard are connected to different serial interfaces for making serial transfer; a printer and a scanner to different parallel interfaces for making parallel transfer; a modem to an RS-232C for making serial transfer; and an external memory to an SCSI interface for making parallel transfer. Moreover, an interface with the same item of peripheral equipment may vary with the computer or equipment manufacturer.
The existence of different interfaces as described above makes it difficult to set computer bodies compatible with any peripheral equipment or integrate the computer body with the peripheral equipment; the problem is that there develops inconvenience in handling computers and peripheral equipment, thus increasing the manufacturing cost. In order to solve the problem, a USB (Universal Serial Bus) interface for use in integrating various interfaces has entered the computer field. Further, it takes on a new aspect that Mini-B interfaces for small-sized peripheral equipment including digital cameras and portable music players are to be added to USB interfaces.
Although the USB interface is a serial interface for making serial transfer, its transmission speed is by far improved in comparison with that of the related serial interface and is advantageous in that the USB interface is capable of simply connecting the computer body and the peripheral equipment at lower cost. Moreover, new cable connectors are being provided so as to conform to new interfaces like this.
FIG. 5 shows a USB connector conforming to such a USB interface as described in JP-A-2000-223218 by way of example. A USB connector 100 has a jack 101 to be directly attached to a printed circuit board (not shown) with electronic devices including transistors and capacitors mounted thereon or to a printed circuit board (not shown) without electronic devices mounted thereon but with only a wiring conductor formed thereon and a plug 120 that is inserted into the jack 101. When the plug 120 and the jack 101 are fitted together a computer body (not shown) and peripheral equipment (not shown) are electrically connected together.
The jack 101 has a shield shell 102 formed by bending a conductive board and an insulating plastic portion 115 with a plurality of jack terminals 110 fixed thereto inside the shield shell 102. Each jack terminal 110 has an elastic contact portion 111 in one side end portion and an external directly-attached type terminal portion 112 in the other side end portion, the jack terminal 110 being elbow-shaped. The jack terminal 110 is such that a substantially intermediate portion between the elastic contact portion 111 and the external directly-attached type terminal portion 112 is fixed to the plastic portion 115 and that the bent front end of the elastic contact portion 111 mates with the front end portion of the plastic portion 115 and is elastically held therein.
A mating space 103 for receiving the opposite plug 120 is formed inside the wall portion of the shield shell 102. A mounting leg portion 104 extending vertically downward is formed on a base wall 102b. The mounting leg portion 104 is fixed by solder to the circuit board (not shown).
The plug 120 inserted into the jack 101 has a plastic housing 121 and a cylindrical shield case 122 that is held in the housing 121. The mating portion 123 of the shield case 122 fitted into the shield shell 102 is projected from the housing 121 and the base portion 124 of the shield case 122 is provided in a buried condition. A terminal holding portion 137 with plug terminals 130 fixed thereto and an insertion space 136 for receiving the plastic portion 115 of the jack 101 are formed inside the mating portion 123.
Each plug terminal 130 is formed with an electrical contact portion 131 for making contact with the elastic contact portion 111 of the jack terminal 110 in one side end portion and with an electrical-wire connecting portion (not shown) in the other end portion, the plug terminal 130 being held straightly. The electrical contact portion 131 is fixed onto the top face of the terminal holding portion 137 and the electrical-wire connecting portion is connected to an electrical wire (not shown) located in the inner part of the housing 121.
However, the related USB connector involves the following problems. Even while the jack 101 and the plug 120 are connected in a latched condition, there is still fear of causing the plug 120 to come off the jack 101 when vibration or external force is applied to them. This latching structure is arranged so that the latching operation is performed by fitting opposed lock pieces 105 provided in the upper wall 102a and the base wall 102b of the shield shell 102 respectively into hole portions 125 provided in the upper wall 122a and the base wall 122b of the shield case 122. As each lock piece 105 is shaped like a V having an inclined plane on both sides, its latching force is weak and when vibration or external force inadvertently acts on either jack 101 or plug 120, the hole portion 125 may slide along the inclined plane 105a on one side of the lock piece 15 whereby to release the latching of the plug 120.
On the other hand, in case that the elastic force of the lock pieces 105 is strengthened in order to prevent the plug 120 from easily slipping off the jack 101, another problem arises in that the plug 120 will not pulled out even by giving the plug 120 a jerk. In a word, the elastic force of the lock pieces 105 is difficult to adjust; the latching of the lock pieces 105 is released inadvertently when it is unnecessary to release the latching thereof or conversely cannot be released when it is necessary to do so.
In addition, because the opposed lock pieces 105 are provided in the opposed wall portions 102a and 102b respectively, the shield shell 102 has no slide guide face for use when the shield case 122 is slidably fitted in and the vertical positioning of the plug 120 is not carried out, so that it is feared that backlash is produced in the vertical direction.
Further, though it has been arranged to keep the jack 101 and the plug 120 in the latched condition by dropping the lock pieces 105 into the hole portions 125, the latched condition lacks the click feeling of restraint and despite the fact that the plug 120 is not connected to the jack 101 in a completely latched condition, it is likely that the latched condition is mistaken for an achieved latched condition.